Old St Peter's Basilica in Rome stood for over eleven centuries until it was demolished to make room for today's church on the same Vatican site. Its last eyewitness, Maffeo Vegio, explained to the Roman hierarchy how revival of the papacy, whose prestige after the exile to Avignon had been diminished, was inseparable from a renewed awareness of the primacy of Peter's Church. To make his case, Vegio wrote a history founded on credible written and visual evidence. The text guides us through the building's true story in its material reality, undistorted by medieval guides. This was its living memory and a visualization of the continuity of Roman history into modern times. This volume makes available the first complete English translation of Vegio's text. Accompanied by full-color digital reconstructions of the Basilica as it appeared in Vegio's day.